Palatability - an important factor in dairy nutrition

The use of flavors in animal nutrition can be traced back for more than 150 years ago, with the main purpose to increase feed intake. For example, in the UK ground aniseed was sprinkled onto cattle feed to improve palatability already in the early twentieth century. Among all species, cows are known to have the most taste buds with about 25,000 compared to humans (7,000) and dogs (only about 1,700). Thus, using flavors to ensure feed palatability is a viable means to enhance feed intake and performance.

            One of the challenges for the nutritionist is to create nutritious, economically viable yet palatable feeds. However, nutrition can only begin when the feed is consumed by the animal. Flavors can be used to provide more flexible choice of raw materials to be used. A wide range of by-products available to feed formulation allows nutritionists to create more economical feed rations.

Table 1: Factors that reduce palatability.

Bitter tastes, high levels of these ingredients that contain these compounds can depressed feed intake: Tannins (Sorghum) Alkaloids (lupins) Glucosinolates (rapeseed meal) Saponins (beans, peas, alfalfa) Spoiled foods Toxins

Minerals    Calcined magnesite (MgO)    Zinc oxide (ZnO)

Medication

            Taste is important as the first line of defense for animals to select their feeds, and initiate and stimulate the feeding response. Taste as sensory response invoked by feed is either reflected in intake rate when only one choice of feed is given or by preference the animal has when there is choice. The taste signalizes the animal previous post-ingestive effects associated with its sensory properties and also interacts with the nutrient requirements of the animal.

            When it comes to dairy cow production, the main goals are to produce more milk of high quality and healthy calves. In order to reach the goal of having high yielding cows, the good health of the calf is a predisposing factor. The better the feed intake the more likely that the calf is and remains healthy. Looking at the lactating cow, an adequate feed intake is the key to high milk yield and therefore the economic success of the operation. However, a high dry matter intake (DMI) is not just the key to support milk production, but also prevent metabolic diseases and fertility. Flavor can be strategically used during all production stages to stimulate appetite and increase DMI.

Mammals are much more sensitive to bitter tastes. Even palatable ingredients can taste poor if not fresh.

Palatability response of calves

A trial was carried out on three different farms in France with Broutard calves. The experiment on Farm 1 included 24 animals aged between 1 to 1.5 months; Farm 2 had 12 animals aged 1 month and Farm 3 used 20 animals aged 4 months, a total of 56 calves. The calves were kept on grass with the cows and were offered a choice of two different starter feeds over a period of 20 days. One was common starter feed and the other feed contained the flavor at 400g/ton. During the trial period feed consumption of each feed was measured daily.

Table 2: Average daily feed intake of each starter feed when offered as a choice over 20 days.

Farm (months of age)	Control (g/day)	Flavor (g/day)	Difference
Farm 1 (1-1.5)	600	900	+50%
Farm 2 (1)	400	650	+53%
Farm 3 (4)	1,200	1,670	+39%

            The addition of Flavor increased average daily feed intake (Table 2). Thus, it can be concluded that addition of Flavor to starter diets can increase average daily feed intake for young calves.

Palatability response of milking cows

The trial was carried out at a commercial unit in Italy equipped with a Lely Astronaut milking robot milking 66 cows. The cows were not visiting the milking robot frequently enough, so three weeks after trial began, Flavor was added to the feed offered during milking to make it more attractive to cows. The differences in number of milkings and refusals (cow returns to milking machine too soon after being milked and is refused entry) were evaluated.

Table 3. Average number of daily milkings and refusals.

	No Flavor	Flavor	Difference, %
Av. Daily milkings/cow	2.54	2.75	+8.3
Av. Refusals/day	30.0	75.3	+151

            The average number of milkings per cow and day that clearly illustrates an increase in number of milkings after introducing the flavor to the feed, the number of milking per cow increased from 2.54 to 2.75 times per day (Figure 1). In contrast, after the inclusion of the flavor, the number of refusals increased dramatically from 30 to 75.3 times per day (Figure 2).

  Figure 1: Average milking per cow per day during the trial.

 Figure 2: Number of refusals (attempts to go inside milking robots) per day. 

Conclusion

Calves and milking cows showed good response in terms of feed intake and their performance following the addition of the flavor. This indicates that flavors are very important for the animals as they are the cornerstone of the feeding behavior, to stimulate the feeding response, improve palatability and acceptability and lastly, offer nutritionists flexibility to use a wider range of feed raw materials.

By:
Peache Deleon & Kevin Liu